Transformer or inductor assembly

ABSTRACT

A transformer or inductor assembly whose magnetic circuit consists of stacked yoke and core laminations, the yoke laminations forming a channel in which the core laminations and a coil wound about the core laminations are received. An outer protective shell of sheet material is fastened to the magnetic circuit by edge portions of the sheet material received in a groove which extends in the yoke in the magnetically neutral zone of the circuit.

United States Patent Wresner [451 Jan. 18, 1972 TRANSFORMER OR INDUCTOR References Cited ASSEMBLY UNITED STATES PATENTS [721 p Aumia 1,174 225 3/l9l6 Bliss ..-.336/2l0 x [73] Assignee: Dr. Walter Zumtobel, Dombirn, Austria 2,472,150 6/1949 p X 3,078,429 2/1963 'Wiesner ..336/83 [22] Filed: Jan. 27, 1971 1 21 Appl. b; 0 0 Primary Examiner-Thomas J. Kozma H M Attomey-Kelman and Bennan I 57 ABSTRACT [30] Foreign Application Priority Data l 1 A transformer or inductor assembly whose magnetic circuit Feb. 5, 1970 Austrla ..1Q39/70 consists of stacked yoke core laminations, the yoke laminations forming a channel in which the core laminations [52] US, Cl. ..336/83, 336/84, 336/90, and a coil wound about the core lamination are received A 336/210 336/212 outer protective shell of sheetmateria'l is fastened to the mag- [51] 7 15/02 netic circuit by edge portions of the sheet material received in [58] Field of Search ..336/83, 84, 210, 212, 192, a groove which extends in h yoke in the magnetically neutral zone of the circuit. 1

14 Claims, Drawing TRANSFORMER R INDUCTOR ASSEMBLY This invention relates to transformers or inductors, and is particularly concerned with improvements in a transformer or inductor assembly whose magnetic circuit has a core portion, and a yoke portion constituted by respective stacks of laminations, an electrically conductive coil wound about the core portion for generating a magnetic field in the magnetic circuit when passed by an electric current, and a shell substantially enveloping the magnetic circuit.

The shell mechanically protects the other elements of the assembly and may be provided conveniently'with mounting elements for fastening the assembly to a support. One known shellconsist's of a tubular element of uniform cross section into which a subassembly of the yoke, core, and coil is axially inserted. Such insertion of the close fitting subassembly is relatively difficult and costly in labor.

It has therefore been proposed to use a split shell whose halves are provided with flanges and are connected by welding or otherwise fastening the flanges to each other. The flanges or similar projecting shell portions significantly increase the overall dimensions of the assembly, an often important disadvantage. 1

An object of the invention is the provision of a transformer or inductor assembly which combines the simple assembly method of a split. shell with the compactness inherent in the use of a tubular shell. 7 v

With this object and others in view, as will become apparent hereinafter, the invention provides an assembly of the general type described above with an elongated groove in the yoke portion within the neutral zone of the magnetic circuit. The shell employed essentially consists of sheet material, and two edge portions of the sheet material are received in the groove, thereby securing the shell to the magnetic circuit.

Other features and many of the attendant advantages of this invention will be appreciated readilyas the invention becomes better understood by reference to the following detaileddescription of preferred embodiments when considered in connection with the appended drawing in which:

I FIG. 1 shows an inductor assembly of the invention in a perspective view and partly in section;

- FIGS. 2 and 3 illustrate modifications of the device of FIG. 1 in corresponding views;

FIG. 4 shows the elements of the assembly of FIG. 3 prior to The assembly shown in FIG. 1 is prepared by first winding the coil 4 on the stack of core laminations 2, inserting the subassembly so formed in the channel of the stacked yoke laminations 3, and ultimately enveloping the yoke with the sheet metal shell 8. The edge portions 9 may be offset angularly from adjacent parts of the sheet metal body in the final assembly step by means of a suitably contoured roller which is run along the groove 7, or in any other desired manner.

The assembly does not have outwardly projecting flanges or lugs except those that may be needed for fastening theshell8 to a supporting structure, and have been omitted from the drawing, and it is very simple to insert the subassembly of core and yoke laminations 2, 3 and of the coil 4 into the split shell Referring now tothe drawingin detail, and initially to FIG.

ali ed yoke laminations thus defines a channel elongated in the direction of the arrow 5 and enclosing the core laminations 2 and a coil 4 of the electrically conductive, insulated wire which is wound about the core. The structure described so far is conventional and it depends on the arrangement of the wires in the coil'4, not itself relevant to this invention, whether the device constitutes an inductor or a transformer. When electric current passes the coil 4, a magnetic field perpendicular to the arrow 5 is generated in the magnetic circuit as indicated bycurved arrows 6, and the magnetic circuit has a magnetically neutral zone in the longitudinal plane of symmetry of the coil through the yoke 3.

The yoke laminations 3 are each formed with a V-shaped notch in the magnetically neutral zone, and the notches are aligned in the direction of the arrow 5 to form an elongated groove 7. The stack of yoke laminations 3 is conformingly enveloped by a sheet metal shell 8 which is split. The two edge portions 9 of the shell 8 are received in the groove 7, thereby securing the shell on the magnetic circuit 1.

The assembly becomes even simpler if the protective shell is split along two lines into two identical sheet metal bodies 8', as shown in FIG. 2, each body being approximately U-shaped in cross section and having two angularly ofl'set edge portion 9'. The laminations of the modified embodiment differ from those described with reference to FIG. 1 only by two grooves 7 being formed in opposite outer edges in the yoke laminations 3'. The two grooves 7 thus are elongated in a common direction and are transversely open in opposite directions. Both grooves are located in the neutral zone of the magnetic circuit. v

The assembly of an inductor or transformer unit of the general type illustrated in FIG. 2 is further simplified by the use of lor I-I-shaped'core laminations 2 shown in FIG. 3 and known in themselves, which jointly form two troughs retaining respective parts of the coil 4' and of two stacks of yoke laminations 3"; Theyoke laminations 3" are each approximately U-shaped. Each yoke lamination has two leg portions 10 directed toward the leg portions of a yoke lamination in the other stack sothat the two stacks jointly define a channel which receives the wound core laminations 2 in the ultimate assembly. Oblique terminal faces 11 of the leg portions bound two' grooves 7 arranged as described with reference to FIG. 2 and receiving the edge portions of two shell halves 8'.

- In building the assembly shown in FIG. 3, the coil 4 is first wound on the stacked core laminations 2, and the shell halves 8 are assembled with respective stacks of yoke laminations 4 The tree subassemblies thereby formed are shown in FIG.

4. The ultimate assembly merely involves sliding the yoke laminations 3" over the stack of core laminations 2'. A tight fit between the stamped laminations in the core and in the yoke holds the assembly parts in position without further use of fasteners. 7

It is a common feature of the assemblies of the invention that significant stray fields cannot be generated along the grooves 7 because the grooves are located in the magnetically neutral zone of the iron circuit. The sheet metal shell 8 can be manufactured on a power break, and the trough-shaped sheet metal bodies 8 which form the shell in the devices of FIGS. 2 and 3 are produced with even greater case on such machines, and may be snapped over the yoke laminations 3' and 3" and held in place largely by their own resiliency.

The yoke laminations 3a of the assembly partly shown in FIG. 5 have terminal faces 11' on their legs which are slightly undercut so as to form ribs 12 along the open side of the groove bounded by the faces 11'. The edge portions of the associated shell halves 8" are offset at an acute angle to conformingly envelope the ribs 12 and to extend into the undercuts. This arrangement does not rely on the resiliency of the shell halves for securing the shell to the magnetic circuit.

parts of the unitary sheet metal piece which constitutes the shell half 8". As is not explicitly shown, but is obvious from FIG. 6, the final assembly partly shown in FIG. includes another subassembly which is the mirror image of the device shown in FIG. 6, and a two-part core, the laminations of the two core parts being held together by respective coil parts and inserted in the parts of the channel respectively bounded by the stack parts I and II.

The lead wires 13 which connect the two nonillustrated coil parts to each otherv and to external terminals, not shown, are conveniently located in the groove between the end faces 11 of the yoke laminations 3a. The wires may be protected by a strip 14 of sheet metal which forms a cover for the groove and is held in position by resilient engagement of its longitudinal edges with the undercuts under the ribs 12. 7

As is shown in FIG. 7, a separate cover may be dispensed with by modifying the dimensions of the yoke laminations 3b so as to make the elongated gap between the ribs 12 narrow enough to be almost completely filled by the creased portions of the shell halves 8" which separate the edge portions from the main part of each shell half.

The sheet stock which constitutes the several shells and shell halves described above and illustrated in the drawing may consist of iron or like ferromagnetic material, or it may consist of a nonferrous metal such as aluminum or copper whose electric conductivity is much higher than that of iron. Ultimately, a binary laminate of ferromagnetic and nonferrous, electrically highly conductive metal may be used depending on the intended mode of operation of the shell beyond its function of protecting'other elements of the assembly.

A ferromagnefic shell or a ferromagnetic layer in a shell of laminated metal provides magnetic shielding against stray fields and actually functions as a part of the magnetic circuit. A shell of nonferrous metal having good electrical conductivity absorbs stray fields by generating eddy currents which counteract the stray fields. When it is desired to combine both effects by the use of a laminated shell, the conductive layer is located near the principal magnetic circuit of the assembly, and the ferromagnetic material forms an outer layer remote from the circuit.

It should be understood, of course, that the foregoing disclosure relates only to preferred embodiments of the. invention, and that it is intended to cover all changes and modifications of the examples of the invention herein chosen for the purpose of the disclosure which do not constitute departures from the scope and spirit of the invention defined in the appended claims. I

What is claimed is:

1. In a transformer or inductor assembly having a magnetic circuit, the magnetic circuit having a core portion and a yoke portion, said portions including respective stacks of laminations, said circuit having a magnetically neutral zone; and electrically conductive coil wound about said core portion and generating a magnetic field in said circuit when passed by electric current; and a shell substantially enveloping said magnetic circuit, the improvement which comprises:

a. said yoke portion being formed with an elongated groove in said neutral zone,

b. said shell essentially consisting of sheet material,

c. two edge portions of said sheet material being received in said groove and thereby securing said shell on said magnetic circuit.

2. In an assembly as set forth in claim I, said yoke portion being formed with a second groove in said zone, said grooves being elongated in a common direction and open in opposite directions transverse to said common direction, said shell including two bodies of said sheet material, each groove receiving respective edge portions of said bodies.

3. In an assembly as set forth in claim 2, the laminations of said yoke portion being substantially U-shaped and constituting two stacks, each yoke lamination having two leg portions directed toward the leg portions of a yoke lamination in the other stack m such a manner that the two stacks define a channel, said core portion and said coil being received in said chan nel, respective terminal faces of the leg portions bounding said grooves. Y

4. In an assembly as set forth in claim 3, said terminal faces being formed with respective undercuts aligned longitudinally of the associated groove and open toward said groove, said edge portions being partly received in said undercuts.

5. In an assembly as set forth in claim 2, said bodies being approximately U-shaped in cross section transverse to the direction of elongation of said grooves and said sheet material being metallic.

6. In an assembly as set forth in claim 1, the laminations of said yoke portion being frame-shaped, whereby the stack of yoke laminations defines a channel, said core portion and said coil being received in said channel.

7. In an assembly as set forth in claim 1, said stacks being elongated in the direction of elongation of said groove.

8. In an assembly as set forth in claim 7, said direction being perpendicular to said field.

9. In an assembly as set forth in claim 1, a wire lead connected to said coil and received in said groove.

10. In an assembly as set forth in claim 9, a cover member outwardly closing said groove. 1

l 1. In an assembly as set forth in claim 1, said sheet material being ferromagnetic.

12. In an assembly as set forth in claim 1, said sheet material being nonferrous and metallic, and having an electrical conductivity higher than that of iron.

13. In an assembly as set forth in claim 1, said sheet material being laminar and including an inner layer adjacent said magnetic circuit essentially consisting of nonferrous metal having an electrical conductivity higher than that of iron, and an outer ferromagnetic layer remote from said magnetic circuit.

14. In an assembly as set forth in claim 1, said stacks, said groove, and said coil having each two parts spacedly aligned in the direction of elongation of said groove, respective parts of a unitary piece of said sheet material enveloping the two parts of each stack, and a wire lead connecting the two parts of said coil and being received in one of said parts of said groove. 

1. In a transformer or inductor assembly having a magnetic circuit, the magnetic circuit having a core portion and a yoke portion, said portions including respective stacks of laminations, said circuit having a magnetically neutral zone; and electrically conductive coil wound about said core portion and generating a magnetic field in said circuit when passed by electric current; and a shell substantially enveloping said magnetic circuit, the improvement which comprises: a. said yoke portion being formed with an elongated groove in said neutral zone, b. said shell essentially consisting of sheet material, c. two edge portions of said sheet material being received in said groove and thereby securing said shell on said magnetic circuit.
 2. In an assembly as set forth in claim 1, said yoke portion being formed with a second groove in said zone, said grooves being elongated in a common direction and open in opposite directions transverse to said common direction, said shell including two bodies of said sheet material, each groove receiving respective edge portions of said bodies.
 3. In an assembly as set forth in claim 2, the laminations of said yoke portion being substantially U-shaped and constituting two stacks, each yoke lamination having two leg portions directed toward the leg portions of a yoke lamination in the other stack in such a manner that the two stacks define a channel, said core portion and said coil being received in said channel, respective terminal faces of the leg portions bounding said grooves.
 4. In an assembly as set forth in claim 3, said terminal faces being formed with respective undercuts aligned longitudinally of the associated groove and open toward said groove, said edge portions being partly received in said undercuts.
 5. In an assembly as set forth in claim 2, said bodies being approximately U-shaped in cross section transverse to the direction of elongation of said grooves and said sheet material being metallic.
 6. In an assembly as set forth in claim 1, the laminations of said yoke portion being frame-shaped, whereby the stack of yoke laminations defines a channel, said core portion and said coil being received in said channel.
 7. In an assembly as set forth in claim 1, said stacks being elongated in the direction of elongation of said groove.
 8. In an assembly as set forth in claim 7, said direction being perpendicular to said field.
 9. In an assembly as set forth in claim 1, a wire lead connected to said coil and received in said groove.
 10. In an assembly as set forth in claim 9, a cover member outwardly closing said groove.
 11. In an assembly as set forth in claim 1, said sheet material being ferromagnetic.
 12. In an assembly as set forth in claim 1, said sheet material being nonferrous and metallic, and having an electrical conductivity higher than that of iron.
 13. In an assembly as set forth in claim 1, said sheet material being laminar and including an inner layer adjacent said magnetic circuit essentially consisting of nonferrous metal having an electrical conductivity higher than that of iron, and an outer ferromagnetic layer remote from said magnetic circuit.
 14. In an assembly as set forth in claim 1, said stacks, said groove, and said coil having each two parts spacedly aligned in the direction of elongation of said groove, respective parts of a unitary piece of said sheet material enveloping the two parts of each stack, and a wire lead connecting the two parts of said coil and being received in one of said parts of said groove. 